The matrix proteins of bones and teeth play key roles in the structure and functions of these tissues. Our objective was to study their function and regulation using a combination of in vitro and in vivo analysis. A major challenge for the study of human gene function and regulation is the extreme inefficiency of DNA transfer DNA into human non-transformed cultured cells. In order to devise new methods to overcome this blockade we tested two adenoviral based procedures using marrow stromal fibroblasts and trabecular bone cells both derived from human skeletal material. Adenoviruses containing b-galactosidase recombinant genes showed substantial gene transfer indicating they are ideal for these unique cell types. We also tested adenoviruses modified with poly-lysine additionally and found they transferred genes into mulitlayer highly differentiated non-dividing cells also with high efficiency. In order to test the feasibility of using this ADV based procedure in human skeletal bone cells we used it to rescue estrogen responsiveness in cells unable to make the estrogen receptor alpha (HERKO). Our data showed that ER alpha dependent gene activation by estrogen was possible and, further, was influenced by treatment with TGF-beta1. IL6 production in ER rescued HERKO was also influenced by treatment with TGF-beta. This is the first approach of its kind to clarify the relationship of growth factors to the function of the estrogen receptor human bone. To determine the function of matrix proteins in vivo we generated bgn-deficient mice. While apparently normal at birth, these mice display a phenotype characterized by reduced growth and bone mass due to the absence of bgn. To our knowledge, this is the first report that deficiency of a non-collagenous extracellular matrix protein (ECM) that leads to a skeletal phenotype that is marked by low bone mass which becomes more obvious with age. These mice may serve as an animal model to study the role of ECM proteins in osteoporosis. - matrix, adenovirus, estrogen receptor, biglycan, bone